Osmotic delivery device comprising an insulinotropic peptide and uses thereof

ABSTRACT

A suspension formulation of an insulinotropic peptide (e.g., glucagon-like peptide-1 (GLP-1) or exenatide) is described. The suspension formulation comprises (i) a non-aqueous, single-phase vehicle, comprising one or more polymer and one or more one solvent, wherein the vehicle exhibits viscous fluid characteristics, and (ii) a particle formulation comprising the insulinotropic peptide, wherein the peptide is dispersed in the vehicle. The particle formulation further includes a stabilizing component comprising one or more stabilizers, for example, carbohydrates, antioxidants, amino acids, and buffers. Devices for delivering the suspension formulations and methods of use are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/927,432, filed Nov. 15, 2010, now U.S. Pat. No. 8,940,316, which is adivisional of U.S. patent application Ser. No. 12/148,896, filed Apr.22, 2008, now U.S. Pat. No. 8,299,025, which claims the benefit of U.S.Provisional Application Ser. No. 61/072,202, filed Mar. 28, 2008, andU.S. Provisional Application Ser. No. 60/926,005, filed Apr. 23, 2007,and which is a continuation-in-part of U.S. patent application Ser. No.11/347,562, filed Feb. 3, 2006, now U.S. Pat. No. 8,114,437, whichclaims the benefit of U.S. Provisional Application No. 60/650,225, filedFeb. 3, 2005. Each of the above-referenced applications is hereinincorporated by reference in its entirety.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has beensubmitted in ASCII format via EFS-Web and is hereby incorporated byreference in its entirety. Said ACSII copy, created on Jan. 23, 2015, isnamed ITCA-036C01US_SequenceListing_ST25.txt and is 1,343 bytes in size.

TECHNICAL FIELD

The present invention relates to organic chemistry, formulationchemistry, and peptide chemistry applied to pharmaceutical research anddevelopment. Aspects of the present invention provide suspensionformulations of insulinotropic peptides for use in mammals and for thetreatment of diseases or conditions.

BACKGROUND OF THE INVENTION

Glucagon-like peptide-1 (GLP-1) is ‘important hormone and a fragment ofthe human proglucagon molecule. GLP-1 is rapidly metabolized by apeptidase (dipeptidylpeptidase IV or DPP-IV). A fragment of GLP-1,glucagon-like peptide-1 (7-36) amide (glucagon-like insulinotropicpeptide, or GLIP) is a gastrointestinal peptide that potentiates therelease of insulin in physiologic concentrations (Gutniak M., et al., NEngl J Med. 1992 May 14; 326(20):1316-22). GLP-1 and GLP-1(7-36)amideare incretins. Incretins are gastrointestinal hormones that cause anincrease in the amount of insulin released from beta cells after eating.

Food intake, as well as stimulation of the sympathetic nervous system,stimulates secretion of GLP-1 in the small intestine of mammals.Further, GLP-1 stimulates the production and secretion of insulin, therelease of somatostatin, glucose utilization by increasing insulinsensitivity, and, in animal studies, also stimulates beta-cell functionand proliferation.

GLP-1(7-36)amide and GLP-1(7-37) normalize fasting hyperglycemia in Type2 diabetic patients (Nauck, M. A., et al., Diabet. Med.15(11):937-45(1998)).

Exendin-4 is an incretin mimetic (i.e., it mimics physiological effectsof incretins) purified from Heloderma suspectum venom (Eng, J., et al.,J. Biol. Chem. 267:7402-05 (1992)) and shows structural relationship tothe incretin hormone GLP-1(7-36)amide. Exendin-4 and truncatedexendin-(9-39)amide specifically interact with the GLP-1 receptor oninsulinoma-derived cells and on lung membranes (Goke R, et al., J Biol.Chem. 268:19650-55 (1993)). Exendin-4 has approximately 53% homology tohuman GLP-1 (Pohl, M., et al., J Biol. Chem. 273:9778-84 (1998)). UnlikeGLP-1, however, exendin-4 is resistant to degradation by DPP-IV. Aglycine substitution confers resistance to degradation by DPP-IV (Young,A. A., et al., Diabetes 48(5):1026-34(1999)).

SUMMARY OF THE INVENTION

The present invention relates to suspension formulations comprising aparticle formulation and a suspension vehicle, as well as devicescomprising such formulations, methods of making such formulations anddevices, and methods of use thereof.

In one aspect, the present invention relates to a suspension formulationcomprising, a particle formulation comprising an insulinotropic peptideand one or more stabilizer selected from the group consisting ofcarbohydrates, antioxidants, amino acids, buffers, and inorganiccompounds. The suspension formulation further comprises a non-aqueous,single-phase suspension vehicle comprising one or more polymer and oneor more solvent. The suspension vehicle exhibits viscous fluidcharacteristics and the particle formulation is dispersed in thevehicle.

In one embodiment, the suspension formulation comprises a particleformulation comprising an insulinotropic peptide, a disaccharide (e.g.,sucrose), methionine, and a buffer (e.g., citrate), and a non-aqueous,single-phase suspension vehicle comprising one or more pyrrolidonepolymer (e.g., polyvinylpyrollidone) and one or more solvent (e.g.,lauryl lactate, lauryl alcohol, benzyl benzoate, or mixtures thereof.

Examples of insulinotropic peptides include, but are not limited to,glucagon-like peptide-1 (GLP-1), exenatide, and derivatives or analoguesthereof. In one embodiment of the invention, the insulinotropic peptideis GLP-1(7-36)amide. In another embodiment of the invention, theinsulinotropic peptide is exenatide.

The particle formulations of the present invention may further comprisea buffer, for example, selected from the group consisting of citrate,histidine, succinate, and mixtures thereof.

The particle formulations of the present invention may further comprisean inorganic compound, for example, selected from the group consistingof citrate, histidine, succinate, and mixtures thereof. NaCl, Na₂SO₄,NaHCO₃, KCl, KH₂PO₄, CaCl₂, and MgCl₂.

The one or more stabilizer in the particle formulations may comprise,for example, a carbohydrate selected from the group consisting oflactose, sucrose, trehalose, mannitol, cellobiose, and mixtures thereof.

The one or more stabilizer in the particle formulations may comprise,for example, an antioxidant selected from the group consisting ofmethionine, ascorbic acid, sodium thiosulfate,ethylenediaminetetraacetic acid (EDTA), citric acid, cysteins,thioglycerol, thioglycolic acid, thiosorbitol, butylated hydroxanisol,butylated hydroxyl toluene, and propyl gallate, and mixtures thereof.

The one or more stabilizer in the particle formulations may comprise anamino acid.

In one embodiment, the solvent of the suspension vehicle of the presentinvention is selected from the group consisting of lauryl lactate,lauryl alcohol, benzyl benzoate, and mixtures thereof. An example of apolymer that can be to formulate the suspension vehicle is a pyrrolidone(e.g., polyvinylpyrrolidone). In a preferred embodiment, the polymer isa pyrrolidone and the solvent is benzyl benzoate.

The suspension formulation typically has an overall moisture contentless than about 10 wt % and in a preferred embodiment less than about 5wt %.

An implantable drug delivery device may be used to contain and deliverthe suspension formulation of the present invention. In one embodimentthe device is an osmotic delivery device.

The suspension formulations of the present invention can be used totreat any of a number of disease states or conditions in a subject inneed of treatment, for example, type II diabetes. In one embodiment, animplantable drug delivery device delivers a suspension formulation ofthe present invention at a substantially uniform rate for a period ofabout one month to about a year. The device may, for example, beimplanted subcutaneously in a convenient location.

The present invention also includes methods of manufacturing thesuspension formulations, particle formulations, suspension vehicles, anddevices of the present invention as described herein.

These and other embodiments of the present invention will readily occurto those of ordinary skill in the art in view of the disclosure herein.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B presents the sequences of two examples of insulinotropicpeptides: FIG. 1A, glucagon-like peptide 1 (7-36) amide(GLP-1(7-36)amide) (SEQ ID NO:1), and FIG. 1B, synthetic exenatidepeptide (SEQ ID NO:2).

FIG. 2 presents data for group mean body weights of test animals treatedby continuous delivery of exenatide from a DUROS® (ALZA Corporation,Mountain View, Calif., licensed to Intarcia Therapeutics, Inc., Hayward,Calif.) device. In the figure, the vertical axis is mean body weight ingrams (Body Weight (g)) and the horizontal axis is the day (Day). Theobese animals of Group 1 (closed diamonds) were the control group towhich 0 mcg of exenatide from a DUROS® device was administered per day.The animals of Group 2 (closed squares) were obese animals to which 20mcg of exenatide from a DUROS® device was administered per day. Theanimals of Group 3 (closed triangles) were lean animals to which 20 mcgof exenatide was administered per day.

FIG. 3 presents data for group mean blood glucose concentrations of testanimals treated by continuous delivery of exenatide from a DUROS®device. In the figure, the vertical axis is mean blood glucose in mg/dL(Blood Glucose (mg/dL)) and the horizontal axis is the day (Day),wherein each day has three associated blood glucose values (A, B, C).Day −1A is a fasting blood glucose value and Day 8A is a fasting bloodglucose value. The obese animals of Group 1 (closed diamonds) were thecontrol group to which 0 mcg of exenatide was administered per day. Theanimals of Group 2 (closed squares) were obese animals to which 20 mcgof exenatide from a DUROS® device was administered per day. The animalsof Group 3 (closed triangles) were lean animals to which 20 mcg. ofexenatide from a DUROS® device was administered per day.

FIG. 4 presents data for group mean HbAlc values of test animals treatedby continuous delivery of exenatide from a DUROS® device. In the figure,the vertical axis is mean percent HbAlc (HbAlc (%)) and the horizontalaxis is the day (Day). The obese animals of Group 1 (closed diamonds)were the control group to which 0 mcg of exenatide was administered perday. The animals of Group 2 (closed squares) were obese animals to which20 mcg of exenatide was administered per day. The animals of Group 3(closed triangles) were lean animals to which 20 mcg of exenatide from aDUROS® device was administered per day.

DETAILED DESCRIPTION OF THE INVENTION

All patents, publications, and patent applications cited in thisspecification are herein incorporated by reference as if each individualpatent, publication, or patent application was specifically andindividually indicated to be incorporated by reference in its entiretyfor all purposes.

1.0.0 DEFINITIONS

It is to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting. As used in this specification and the appended claims,the singular forms “a,” “an” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, reference to“a solvent” includes a combination of two or more such solvents,reference to “a peptide” includes one or more peptides, mixtures ofpeptides, and the like.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. Although other methods andmaterials similar, or equivalent, to those described herein can be usedin the practice of the present invention, the preferred materials andmethods are described herein.

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions set outbelow.

The terms “peptide,” “polypeptide,” and “protein” are usedinterchangeable herein and typically refer to a molecule comprising achain of two or more amino acids (e.g., most typically L-amino acids,but also including, e.g., D-amino acids, modified amino acids, aminoacid analogues, and/or amino acid mimetic). Peptides may also compriseadditional groups modifying the amino acid chain, for example,functional groups added via post-translational modification. Examples ofpost-translation modifications include, but are not limited to,acetylation, alkylation (including, methylation), biotinylation,glutamylation, glycylation, glycosylation, isoprenylation, lipoylation,phosphopantetheinylation, phosphorylation, selenation, and C-terminalamidation. The term peptide also includes peptides comprisingmodifications of the amino terminus and/or the carboxy terminusModifications of the terminal amino group include, but are not limitedto, des-amino, N-lower alkyl, N-di-lower alkyl, and N-acylmodifications. Modifications of the terminal carboxy group include, butare not limited to, amide, lower alkyl amide, dialkyl amide, and loweralkyl ester modifications (e.g., wherein lower alkyl is C₁-C₄ alkyl).

The terminal amino acid at one end of the peptide chain typically has afree amino group (i.e., the amino terminus). The terminal amino acid atthe other end of the chain typically has a free carboxyl group (i.e.,the carboxy terminus). Typically, the amino acids making up a peptideare numbered in order, starting at the amino terminus and increasing inthe direction of the carboxy terminus of the peptide.

The phrase “amino acid residue” as used herein refers to an amino acidthat is incorporated into a peptide by an amide bond or an amide bondmimetic.

The term “insulinotropic” as used herein refers to the ability of acompound, e.g., a peptide, to stimulate or affect the production and/oractivity of insulin (e.g., an insulinotropic hormone). Such compoundstypically stimulate the secretion or biosynthesis of insulin in asubject.

The phrase “insulinotropic peptide” as used herein includes, but is notlimited to, glucagon-like peptide 1 (GLP-1), as well as derivatives andanalogues thereof, and exenatide, as well as derivatives and analoguesthereof.

The term “vehicle” as used herein refers to a medium used to carry acompound. Vehicles of the present invention typically comprisecomponents such as polymers and solvents. The suspension vehicles of thepresent invention typically comprise solvents and polymers that are usedto prepare suspension formulations of polypeptide particles.

The phrase “phase separation” as used herein refers to the formation ofmultiple phases (e.g., liquid or gel phases) in the suspension vehicle,such as when the suspension vehicle contacts the aqueous environment. Insome embodiments of the present invention, the suspension vehicle isformulated to exhibit phase separation upon contact with an aqueousenvironment having less than approximately 10% water.

The phrase “single-phase” as used herein refers to a solid, semisolid,or liquid homogeneous system that is physically and chemically uniformthroughout.

The term “dispersed” as used herein refers to dissolving, dispersing,suspending, or otherwise distributing a compound, for example, apeptide, in a suspension vehicle.

The phrase “chemically stable” as used herein refers to formation in aformulation of an acceptable percentage of degradation products producedover a defined period of time by chemical pathways, such as deamidation(usually by hydrolysis), aggregation, or oxidation.

The phrase “physically stable” as used herein refers to formation in aformulation of an acceptable percentage of aggregates (e.g., dimers andother higher molecular weight products). Further, a physically stableformulation does not change its physical state as, for example, fromliquid to solid, or from amorphous to crystal form.

The term “viscosity” as used herein typically refers to a valuedetermined from the ratio of shear stress to shear rate (see, e.g.,Considine, D. M. & Considine, G. D., Encyclopedia of Chemistry, 4thEdition, Van Nostrand, Reinhold, N.Y., 1984) essentially as follows:

F/A=μ*V/L   (Equation 1)

where F/A=shear stress (force per unit area),

μ=a proportionality constant (viscosity), and

V/L=the velocity per layer thickness (shear rate).

From this relationship, the ratio of shear stress to shear rate definesviscosity. Measurements of shear stress and shear rate are typicallydetermined using parallel plate rheometery performed under selectedconditions (for example, a temperature of about 37° C.). Other methodsfor the determination of viscosity include, measurement of a kinematicviscosity using a viscometers, for example, a Cannon-Fenske viscometer,a Ubbelohde viscometer for the Cannon-Fenske opaque solution, or aOstwald viscometer. Generally, suspension vehicles of the presentinvention have a viscosity sufficient to prevent a particle formulationsuspended therein from settling during storage and use in a method ofdelivery, for example, in an implantable, drug delivery device.

The term “non-aqueous” as used herein refers to an overall moisturecontent, for example, of a suspension formulation, typically of lessthan or equal to about 10 wt %, preferably less than or equal to about 5wt %, and more preferably less than about 4 wt %.

The term “subject” as used herein refers to any member of the subphylumchordata, including, without limitation, humans and other primates,including non-human primates such as rhesus macaque, chimpanzees andother apes and monkey species; farm animals such as cattle, sheep, pigs,goats and horses; domestic mammals such as dogs and cats; laboratoryanimals including rodents such as mice, rats and guinea pigs; birds,including domestic, wild and game birds such as chickens, turkeys andother gallinaceous birds, ducks, geese, and the like. The term does notdenote a particular age. Thus, both adult and newborn individuals areintended to be covered.

The terms “drug,” “therapeutic agent”, and “beneficial agent” are usedinterchangeably to refer to any therapeutically active substance that isdelivered to a subject to produce a desired beneficial effect. In oneembodiment of the present invention, the drug is an insulinotropicpeptide, e.g., GLP-1, exenatide, and derivatives or analogues thereof.The devices and methods of the present invention are well suited for thedelivery of polypeptides as well as small molecules and combinationsthereof.

The term “osmotic delivery device” as used herein typically refers to adevice used for delivery of one or more beneficial agent (e.g., aninsulinotropic peptide) to a subject, wherein the device comprises, forexample, a reservoir (made, for example, from a titanium alloy) having alumen that contains a suspension formulation (e.g., comprising aninsulinotropic peptide) and an osmotic agent formulation. A pistonassembly positioned in the lumen isolates the suspension formulationfrom the osmotic agent formulation. A semi-permeable membrane positionedat a first distal end of the reservoir adjacent the osmotic agentformulation, as well as a flow modulator (which defines a deliveryorifice through which the suspension formulation exits the device) thatis positioned at a second distal end of the reservoir adjacent thesuspension formulation. Typically, the osmotic delivery device isimplanted within the subject, for example, subcutaneously (e.g., in theinside, outside, or back of the upper arm; or in the abdominal area).

2.0.0 GENERAL OVERVIEW OF THE INVENTION

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to particular types ofdrug delivery, particular types of drug delivery devices, particularsources of peptides, particular solvents, particular polymers, and thelike, as use of such particulars may be selected in view of theteachings of the present specification. It is also to be understood thatthe terminology used herein is for the purpose of describing particularembodiments of the invention only, and is not intended to be limiting.

In one aspect, the present invention relates to a suspensionformulation, comprising a particle formulation and a suspension vehicle.The particle formulation includes, but is not limited to, aninsulinotropic peptide and one or more stabilizer. The one or morestabilizer is typically selected from the group consisting ofcarbohydrates, antioxidants, amino acids, and buffers. The suspensionvehicle is typically a non-aqueous, single-phase suspension vehiclecomprising one or more polymer and one or more solvent. The suspensionvehicle exhibits viscous fluid characteristics. The particle formulationis uniformly dispersed in the vehicle.

In one embodiment of the present invention the insulinotropic peptide isa glucagon-like peptide-1 (GLP-1), a derivative of GLP-1 (e.g.,GLP-1(7-36)amide), or an analogue of GLP-1.

In another embodiment of the present invention insulinotropic peptide isexenatide, a derivative of exenatide, or an analogue of exenatide.

The particle formulation of the present invention typically includes oneor more of the following stabilizers: one or more carbohydrate (e.g., adisaccharide, such as, lactose, sucrose, trehalose, cellobiose, andmixtures thereof); one or more antioxidant (e.g., methionine, ascorbicacid, sodium thiosulfate, ethylenediaminetetraacetic acid (EDTA), citricacid, butylated hydroxyltoluene, and mixtures thereof); and one or morebuffer (e.g., citrate, histidine, succinate, and mixtures thereof). In apreferred embodiment, the particle formulation comprises aninsulinotropic peptide, sucrose, methionine, and citrate buffer. Theratio of insulinotropic peptide to sucrose+methionine is typically about1/20, about 1/10, about 1/5, about 1/2, about 5/1, about 10/1, or about20/1, preferably between about 1/5 to 5/1, more preferably between about1/3 to 3/1. The particle formulation is preferably a particleformulation prepared by spray drying and has a low moisture content,preferably less than or equal to about 10 wt %, more preferably less orequal to about 5 wt %. In another embodiment the particle formulationcan be lyophilized.

The suspension vehicle of the present invention comprises one or moresolvent and one or more polymer. Preferably the solvent is selected fromthe group consisting of lauryl lactate, lauryl alcohol, benzyl benzoate,and mixtures thereof. More preferably the solvent is lauryl lactate orbenzyl benzoate. Preferably the polymer is a pyrrolidone. In someembodiments the polymer is polyvinylpyrrolidone (e.g.,polyvinylpyrrolidone K-17, which typically has an approximate averagemolecular weight range of 7,900-10,800). In one embodiment of thepresent invention the solvent consists essentially of benzyl benzoateand polyvinylpyrrolidone.

The suspension formulation typically has a low overall moisture content,for example, less than or equal to about 10 wt % and in a preferredembodiment less than or equal to about 5 wt %.

In another aspect, the present invention relates to an implantable drugdelivery device, comprising a suspension formulation of the presentinvention. In a preferred embodiment, the drug delivery device is anosmotic delivery device.

The present invention further includes methods of manufacturing thesuspension formulations of the present invention, as well as osmoticdelivery devices loaded with a suspension formulation of the presentinvention. In one embodiment, the present invention includes a method ofmanufacturing an osmotic delivery device comprising, loading asuspension formulation into a reservoir of the osmotic delivery device.

In another aspect, the present invention relates to a method of treatingdiabetes (e.g., diabetes mellitus type 2 or gestational diabetes) in asubject in need of such treatment, comprising delivering a suspensionformulation of the present invention from an osmotic delivery device ata substantially uniform rate. Typically the suspension formulation isdelivered for a period of about one month to about a year, preferablyabout three months to about a year. The method may further includesubcutaneously inserting an osmotic delivery device, loaded with asuspension formulation of the present invention, into the subject.

In further aspects, the present invention relates to methods ofstimulating insulin secretion, suppressing glucagon secretion, slowinggastric emptying, treating diabetic related disorders, treatinghyperglycemia, treating obesity, controlling appetite, reducing weight,and regulating gastrointestinal motility.

2.1.0 Formulations and Compositions

2.1.1 Particle Formulations

In one aspect, the present invention provides a pharmaceuticalcomposition comprising a suspension formulation of an insulinotropicpeptide, for example, GLP-1 or exenatide. The suspension formulationcomprises a non-aqueous, single-phase vehicle including at least onepolymer and at least one solvent. The vehicle preferably exhibitsviscous fluid characteristics. The peptide component comprises theinsulinotropic peptide in a particle formulation that is dispersed inthe vehicle. Typically, the particle formulation includes a stabilizingcomponent comprising one of more stabilizer component selected from thegroup consisting of carbohydrates, antioxidants, amino acids, buffers,and inorganic compounds.

Insulinotropic peptides useful in the practice of the present inventioninclude, but are not limited to, GLP-1 and exenatide.

Bell, G. I., et al., (Nature 302:716-718 (1983)) discovered thatproglucagon (Lund, et al., Proc. Natl. Acad. Sci. U.S.A. 79:345-349(1982); Patzelt, et al., Nature, 282:260-266 (1979)) contained threediscrete, highly homologous peptide regions which were designatedglucagon, glucagon-like peptide 1 (GLP-1), and glucagon-like peptide 2(GLP-2). Lopez, et al., (Proc. Natl. Acad. Sci. U.S.A. 80:5485-5489(1983)) demonstrated that the peptide sequence of GLP-1 was a sequenceof 37 amino acids and that the peptide sequence of GLP-2 was a sequenceof 34 amino acids.

Studies of the structure of rat preproglucagon revealed a similarpattern of proteolytic cleavage resulting in the formation of glucagon,GLP-1, and GLP-2 (Heinrich, G., et al., Endocrinol., 115:2176-2181(1984)). Human, rat, bovine, and hamster sequences of GLP-1 were foundto be identical (Ghiglione, M., et al., Diabetologia, 27:599-600(1984)).

Cleavage of preproglucagon first yields GLP-1(1-37), a 37 amino acidpeptide that has poor insulinotropic activity. A subsequent cleavage ofthe peptide bond between amino acid residues 6 and 7 produces abiologically active GLP-1 referred to as GLP-1(7-37) (by convention theamino terminus of GLP-1(7-37) was assigned number 7 and the carboxyterminus number 37). Approximately 80% of GLP-1(7-37) that is producedin mammals is amidated at the C-terminus after removal of the terminalglycine residue in L-cells, resulting in GLP-1(7-36)amide. Thebiological effects and metabolic turnover of the free acid GLP-1(7-37),and the amide, GLP-1(7-36)amide, are essentially the same. The sequenceof GLP-1(7-36)amide is presented in FIG. 1A.

GLP-1 (including three forms of the peptide, GLP-1(1-37), GLP-1(7-37)and GLP-1(7-36)amide, as well as analogs of GLP-1) have been shown tostimulate insulin secretion (i.e., it is insulinotropic) which inducesglucose uptake by cells and results in decreases in serum glucose levels(see, e g., Mojsov, S., Int. J. Peptide Protein Research, 40:333-343(1992)). Another GLP-1 analogue is liraglutide, which is a long-actingDPP-4-resistant GLP-1 receptor agonist. Liraglutide has 97% identity toGLP-1(7-37). Liraglutide is also called NN-2211 and [Arg34,Lys26]-(N-epsilon-(gamma-Glu(N-alpha-hexadecanoyl))-GLP-1(7-37) (see,e.g., U.S. Pat. No. 6,969,702).

Numerous GLP-1 derivatives and analogues demonstrating insulinotropicaction are known in the art (see, e.g., U.S. Pat. Nos. 5,118,666;5,120,712; 5,512,549; 5,545,618; 5,574,008; 5,574,008; 5,614,492;5,958,909; 6,191,102; 6,268,343; 6,329,336; 6,451,974; 6,458,924;6,514,500; 6,593,295; 6,703,359; 6,706,689; 6,720,407; 6,821,949;6,849,708; 6,849,714; 6,887,470; 6,887,849; 6,903,186; 7,022,674;7,041,646; 7,084,243; 7,101,843; 7,138,486; 7,141,547; 7,144,863; and7,199,217). Accordingly, for ease of discussion herein, the family ofGLP-1 derivatives and analogues having insulinotropic activity isreferred to collectively as GLP-1.

Gastric inhibitory peptide (GIP) is also an insulinotropic peptide(Efendic, S., et al., Horm Metab Res. 36:742-6 (2004)). GIP is a hormonesecreted by the mucosa of the duodenum and jejunum in response toabsorbed fat and carbohydrate that stimulate the pancreas to secreteinsulin. GIP is also known as glucose-dependent insulinotropicpolypeptide. GIP is a 42-amino acid gastrointestinal regulatory peptidethat stimulates insulin secretion from pancreatic beta cells in thepresence of glucose (Tseng, C., et al., PNAS 90:1992-1996 (1993)).

The exendins are peptides that were isolated from the venom of theGila-monster. Exendin-4 is present in the venom of Heloderma suspectum(Eng, J., et al., J. Biol. Chem., 265:20259-62 (1990); Eng., J., et al.,J. Biol. Chem., 267:7402-05 (1992); U.S. Pat. No. 5,424,286). Theexendins have some sequence similarity to several members of theglucagon-like peptide family, with the highest homology, 53%, being toGLP-1(7-36)amide (Goke, et al., J. Biol. Chem., 268:19650-55 (1993)).

Exendin-4 acts at GLP-1 receptors on insulin-secreting beta-TCl cells,dispersed acinar cells from guinea pig pancreas, and parietal cells fromstomach. The exendin-4 peptide also stimulates somatostatin release andinhibits gastrin release in isolated stomachs (Goke, et al., J. Biol.Chem. 268:19650-55 (1993); Schepp, et al., Eur. J. Pharmacol., 69:183-91(1994); Eissele, et al., Life Sci., 55:629-34 (1994)). Based on theirinsulinotropic activities, use of exendin-3 and exendin-4 for thetreatment of diabetes mellitus and the prevention of hyperglycemia hasbeen proposed (U.S. Pat. No. 5,424,286).

Numerous exendin-4 derivatives and analogues (including, e.g., exendin-4agonists) demonstrating insulinotropic action are known in the art (see,e.g., U.S. Pat. Nos. 5,424,286; 6,268,343; 6,329,336; 6,506,724;6,514,500; 6,528,486; 6,593,295; 6,703,359; 6,706,689; 6,767,887;6,821,949; 6,849,714; 6,858,576; 6,872,700; 6,887,470; 6,887,849;6,924,264; 6,956,026; 6,989,366; 7,022,674; 7,041,646; 7,115,569;7,138,375; 7,141,547; 7,153,825; and 7,157,555). Exenatide is asynthetic peptide having the same 39 amino acid sequence as exendin-4.Exenatide is a peptide incretin mimetic that exhibits glucoregulatoryactivities similar to the mammalian incretin hormone glucagon-likepeptide 1 (GLP-1). Incretin hormones are hormones that cause an increasein the amount of insulin released when glucose levels are normal orparticularly when they are elevated. Incretin hormones affect otheractivities defined by insulin secretion, for example, they can reduceglucagon production and delay gastric emptying. Further, incretinhormones may improve insulin sensitivity and possibly increase isletcell neogenesis.

For ease of discussion herein, the family of exendin-4 peptides,including synthetic versions (e.g., exenatide), derivatives andanalogues having insulinotropic activity, is referred to collectively asexenatide.

In one aspect, the present invention provides particle formulations ofinsulinotropic peptides that can be used to prepare suspensionformulations. The insulinotropic peptides of the present invention shallnot be limited by method of synthesis or manufacture and shall includethose obtained from natural sources, or synthesized or manufactured byrecombinant (whether produced from cDNA or genomic DNA), synthetic,transgenic, and gene-activated methods. In preferred embodiments of thepresent invention the insulinotropic peptide is a GLP-1 peptide or anexendin peptide (as described herein above), for example,GLP-1(7-36)amide or exenatide. The present invention also includescombinations of two or more insulinotropic peptides, for example,GLP-1(7-36)amide and GIP.

Particle formulations of the invention are preferably chemically andphysically stable for at least 1 month, preferably at least 3 months,more preferably at least 6 months, more preferably at least 12 months atdelivery temperature. The delivery temperature is typically normal humanbody temperature, for example, about 37° C., or slightly higher, forexample, about 40° C. Further, particle formulations of the presentinvention are preferably chemically and physically stable for at least 3months, preferably at least 6 months, more preferably at least 12months, at storage temperature. Examples of storage temperatures includerefrigeration temperature, for example, about 5° C., or roomtemperature, for example, about 25° C.

A particle formulation may be considered chemically stable if less thanabout 25%, preferably less than about 20%, more preferably less thanabout 15%, more preferably less than about 10%, and more preferably lessthan about 5% breakdown products of the peptide particles are formedafter about 3 months, preferably after about 6 months, preferably afterabout 12 months at delivery temperature and after about 6 months, afterabout 12 months, and preferably after about 24 months at storagetemperature.

A particle formulation may be considered physically stable if less thanabout 10%, preferably less than about 5%, more preferably less thanabout 3%, more preferably less than 1% aggregates of the peptideparticles are formed after about 3 months, preferably after about 6months, at delivery temperature and about 6 months, preferably about 12months, at storage temperature.

To preserve protein stability generally an insulinotropic peptidesolution is kept in a frozen condition and lyophilized or spray dried toa solid state. Tg (glass transition temperature) may be one factor toconsider in achieving stable compositions of peptide. While notintending to be bound by any particular theory, the theory of formationof a high Tg amorphous solid to stabilize peptides, polypeptides, orproteins has been utilized in pharmaceutical industry. Generally, if anamorphous solid has a higher Tg, such as 100° C., peptide products willnot have mobility when stored at room temp or even at 40° C. because thestorage temperature is below the Tg. Calculations using molecularinformation have shown that if a glass transition temperature is above astorage temperature of 50° C. that there is zero mobility for molecules.No mobility of molecules correlates with no instability issues. Tg isalso dependent on the moisture level in the product formulation.Generally, the more moisture, the lower the Tg of the composition.

Accordingly, in some aspects of the present invention, excipients withhigher Tg may be included in the protein formulation to improvestability, for example, sucrose (Tg=75° C.) and trehalose (Tg=110° C.).Preferably, particle formulations are formable into particles usingprocesses such as spray drying, lyophilization, desiccation,freeze-drying, milling, granulation, ultrasonic drop creation,crystallization, precipitation, or other techniques available in the artfor forming particles from a mixture of components. The particles arepreferably substantially uniform in shape and size.

A typical spray dry process may include, for example, loading a spraysolution containing a peptide, for example, an insulinotropic peptide(e.g., GLP-1(7-36)amide or exenatide), and stabilizing excipients into asample chamber. The sample chamber is typically maintained at a desiredtemperature, for example, refrigeration to room temperature.Refrigeration generally promotes stability of the protein. A solution,emulsion, or suspension is introduced to the spray dryer where the fluidis atomized into droplets. Droplets can be formed by use of a rotaryatomizer, pressure nozzle, pneumatic nozzle, or sonic nozzle. The mistof droplets is immediately brought into contact with a drying gas in adrying chamber. The drying gas removes solvent from the droplets andcarries the particles into a collection chamber. In spray drying,factors that can affect yield include, but are not limited to, localizedcharges on particles (which may promote adhesion of the particles to thespray dryer) and aerodynamics of the particles (which may make itdifficult to collect the particles). In general, yield of the spray dryprocess depends in part on the particle formulation.

In one embodiment of the present invention, the particles are sized suchthat they can be delivered via an implantable drug delivery device.Uniform shape and size of the particles typically helps to provide aconsistent and uniform rate of release from such a delivery device;however, a particle preparation having a non-normal particle sizedistribution profile may also be used. For example, in a typicalimplantable osmotic delivery device having a delivery orifice, the sizeof the particles is less than about 30%, preferably is less than about20%, more preferably is less than about than 10%, of the diameter of thedelivery orifice. In an embodiment of the particle formulation for usewith an osmotic delivery system, wherein the delivery orifice diameterof the implant is in a range of, for example, about 0.1 to about 0.5 mm,particle sizes may be preferably less than about 50 microns, morepreferably less than about 10 microns, more preferably in a range fromabout 3 to about 7 microns. In one embodiment, the orifice is about 0.25mm (250 μm) and the particle size is approximately 3-5 μm.

In a preferred embodiment, when the particles are incorporated in asuspension vehicle they do not settle in less than about 3 months atdelivery temperature. Generally speaking, smaller particles tend to havea lower settling rate in viscous suspension vehicles than largerparticles. Accordingly, micron- to nano-sized particles are typicallydesirable. In an embodiment of the particle formulation of the presentinvention for use in an implantable osmotic delivery device, wherein thedelivery orifice diameter of the implant is in a range of, for example,about 0.1 to about 0.5 mm, particle sizes may be preferably less thanabout 50 microns, more preferably less than about 10 microns, morepreferably in a range from about 3 to about 7 microns.

In one embodiment, a particle formulation of the present inventioncomprises one or more insulinotropic peptide, as described above, one ormore stabilizers, and optionally a buffer. The stabilizers may be, forexample, carbohydrate, antioxidant, amino acid, buffer, or inorganiccompound. The amounts of stabilizers and buffer in the particleformulation can be determined experimentally based on the activities ofthe stabilizers and buffers and the desired characteristics of theformulation. Typically, the amount of carbohydrate in the formulation isdetermined by aggregation concerns. In general, the carbohydrate levelshould not be too high so as to avoid promoting crystal growth in thepresence of water due to excess carbohydrate unbound to insulinotropicpeptide. Typically, the amount of antioxidant in the formulation isdetermined by oxidation concerns, while the amount of amino acid in theformulation is determined by oxidation concerns and/or formability ofparticles during spray drying. Typically, the amount of buffer in theformulation is determined by pre-processing concerns, stabilityconcerns, and formability of particles during spray drying. Buffer maybe required to stabilize insulinotropic peptide during processing, e.g.,solution preparation and spray drying, when all excipients aresolubilized.

Examples of carbohydrates that may be included in the particleformulation include, but are not limited to, monosaccharides (e.g.,fructose, maltose, galactose, glucose, D-mannose, and sorbose),disaccharides (e.g., lactose, sucrose, trehalose, and cellobiose),polysaccharides (e.g., raffinose, melezitose, maltodextrins, dextrans,and starches), and alditols (acyclic polyols; e.g., mannitol, xylitol,maltitol, lactitol, xylitol sorbitol, pyranosyl sorbitol, andmyoinsitol). Preferred carbohydrates include non-reducing sugars, suchas sucrose, trehalose, and raffinose.

Examples of antioxidants that may be included in the particleformulation include, but are not limited to, methionine, ascorbic acid,sodium thiosulfate, catalase, platinum, ethylenediaminetetraacetic acid(EDTA), citric acid, cysteins, thioglycerol, thioglycolic acid,thiosorbitol, butylated hydroxanisol, butylated hydroxyltoluene, andpropyl gallate.

Examples of amino acids that may be included in the particle formulationinclude, but are not limited to, arginine, methionine, glycine,histidine, alanine, L-leucine, glutamic acid, iso-leucine, L-threonine,2-phenylamine, valine, norvaline, praline, phenylalanine, trytophan,serine, asparagines, cysteine, tyrosine, lysine, and norleucine.Preferred amino acids include those that readily oxidize, e.g.,cysteine, methionine, and trytophan.

Examples of buffers that may be included in the particle formulationinclude, but are not limited to, citrate, histidine, succinate,phosphate, maleate, tris, acetate, carbohydrate, and gly-gly. Preferredbuffers include citrate, histidine, succinate, and tris.

Examples of inorganic compounds that may be included in the particleformulation include, but are not limited to, NaCl, Na₂SO4, NaHCO₃, KCl,KH₂PO4, CaCl₂, and MgCl₂.

In addition, the particle formulation may include other excipients, suchas surfactants, bulking agents, and salts. Examples of surfactantsinclude, but are not limited to, Polysorbate 20, Polysorbate 80,PLURONIC® (BASF Corporation, Mount Olive, N.J.) F68, and sodium docecylsulfate (SDS). Examples of bulking agents include, but are not limitedto, mannitol and glycine. Examples of salts include, but are not limitedto, sodium chloride, calcium chloride, and magnesium chloride.

All components included in the particle formulation are typicallyacceptable for pharmaceutical use in mammals, in particular, in humans.

Table 1 below presents examples of particle formulation compositionranges for particles comprising exenatide.

TABLE 1 More Preferred Preferred Range Range Range (% by weight) (% byweight) (% by weight) Particle loading in 0.1 to 99.9% 1 to 50% 5 to 40%suspension formulation In Particles Exenatide peptide 1 to 99% 5 to 70%10 to 60% Carbohydrate 0 to 99% 2.5 to 40% 5 to 30% Antioxidant and/or 0to 99% 2.5 to 30% 5 to 30% amino acid Buffer 0 to 99% 10 to 80% 10 to70%

In one embodiment, the exenatide particle formulation comprisesexenatide peptide, sucrose (carbohydrate), methionine (antioxidant), andsodium citrate/citric acid (citrate buffer).

Table 2 below presents examples of particle formulation compositionranges for particles comprising GLP-1.

TABLE 2 More Preferred Preferred Range Range Range (% by weight) (% byweight) (% by weight) Particle loading in 0.1 to 99.9% 1 to 50% 10-50%suspension formulation In Particles GLP-1 peptide 1 to 99% 5 to 95%30-90% Carbohydrate and/or 0 to 99% 0.1 to 30% 2-20% Antioxidant and/oramino acid Buffer 0 to 99% 0.1 to 50% 2-30%

Within these weight percent ranges for components of the particleformulation, some preferred component ratios are as follows:insulinotropic peptide (e.g., exenatide or GLP-1) to antioxidant (e.g.,methionine)—1/10, 1/5, 1/2.5, 1/1, 2.5/1, 5/1, 10/1, preferably betweenabout 1/5 to 5/1, more preferably between about 1/3 to 3/1 (these samecomponent ratios apply to insulinotropic peptide to amino acid ratios);insulinotropic peptide (e.g., exenatide or GLP-1) to carbohydrate (e.g.,sucrose)—1/10, 1/5, 1/2.5, 1/1, 2.5/1, 5/1, 10/1, preferably betweenabout 1/5 to 5/1, more preferably between about 1/3 to 3/1; and/orinsulinotropic peptide (e.g., exenatide or GLP-1) toantioxidant+carbohydrate (e.g., methionine+sucrose)—1/20, 1/10, 1/5,1/2, 5/1, 10/1, 20/1, preferably between about 1/5 to 5/1, morepreferably between about 1/3 to 3/1 (these same component ratios applyto insulinotropic peptide to amino acid+carbohydrate ratios). Thepresent invention also includes ranges corresponding to all of theseratios, for example, between about 1/20 and about 20/1, between about1/10 and about 10/1, between about 1/5 and about 5/1, and so on, as wellas, for example, between about 1/5 and about 3/1, and so on.

In summary, insulinotropic peptides are formulated into dried powders insolid state, which preserve maximum chemical and biological stability ofproteins or peptides. The particle formulation offers long term storagestability at high temperature, and therefore, allows delivery to asubject of stable and biologically effective peptide for extendedperiods of time.

Particle size distribution of the dry particle powder can be wellcontrolled (0.1 micron-20 micron), for example, by using the methods ofspray drying or lyophilization to prepare the particle formulations. Theprocess parameters for formation of the dry powder are optimal toproduce particles with desired particle size distribution, density, andsurface area.

The selected excipients and buffer in the particle formulation mayprovide, for example, the following functions: density modification ofthe dry powder; preservation of the peptide chemical stability;maintenance of the peptide's physical stability (e.g., high glasstransition temperature, and avoiding phase to phase transition);producing homogenous dispersions in suspension by use of bulking agents;modification of hydrophobicity and/or hydrophilicity to manipulate drypowder solubility in selected solvents; and, manipulation of pH duringprocessing and maintenance of pH in the product (for solubility andstability).

The particle formulations of the present invention are exemplifiedherein below with reference to exenatide and GLP-1(7-36)amide asexemplary insulinotropic peptides (see, Example 1 and Example 2). Theseexamples are not intended to be limiting.

2.1.2 Vehicle and Suspension Formulations

In one aspect of the present invention, the suspension vehicle providesa stable environment in which the insulinotropic peptide particleformulation is dispersed. The particle formulations are chemically andphysically stable (as described above) in the suspension vehicle. Thesuspension vehicle typically comprises one or more polymers and one ormore solvents that form a solution of sufficient viscosity to uniformlysuspend the particles comprising the insulinotropic peptide.

The viscosity of the suspension vehicle is typically sufficient toprevent the particle formulation from settling during storage and use ina method of delivery, for example, in an implantable, drug deliverydevice. The suspension vehicle is biodegradable in that the suspensionvehicle disintegrates or breaks down over a period of time in responseto a biological environment. The disintegration of the suspensionvehicle may occur by one or more physical or chemical degradativeprocesses, such as by enzymatic action, oxidation, reduction, hydrolysis(e.g., proteolysis), displacement (e.g., ion exchange), or dissolutionby solubilization, emulsion or micelle formation. After the suspensionvehicle disintegrates, components of the suspension vehicle are absorbedor otherwise dissipated by the body and surrounding tissue of thepatient.

The solvent in which the polymer is dissolved may affect characteristicsof the suspension formulation, such as the behavior of theinsulinotropic peptide particle formulation during storage. A solventmay be selected in combination with a polymer so that the resultingsuspension vehicle exhibits phase separation upon contact with theaqueous environment. In some embodiments of the invention, the solventmay be selected in combination with the polymer so that the resultingsuspension vehicle exhibits phase separation upon contact with theaqueous environment having less than approximately about 10% water.

The solvent may be an acceptable solvent that is not miscible withwater. The solvent may also be selected so that the polymer is solublein the solvent at high concentrations, such as at a polymerconcentration of greater than about 30%. However, typically theinsulinotropic peptide is substantially insoluble in the solvent.Examples of solvents useful in the practice of the present inventioninclude, but are not limited to, lauryl alcohol, benzyl benzoate, benzylalcohol, lauryl lactate, decanol (also called decyl alcohol), ethylhexyl lactate, and long chain (C₈ to C₂₄) aliphatic alcohols, esters, ormixtures thereof. The solvent used in the suspension vehicle may be“dry,” in that it has a low moisture content. Preferred solvents for usein formulation of the suspension vehicle include lauryl lactate, laurylalcohol, benzyl benzoate, and combinations thereof.

Examples of polymers for formulation of the suspension vehicles of thepresent invention include, but are not limited to, a polyester (e.g.,polylactic acid or polylacticpolyglycolic acid), pyrrolidone (e.g.,polyvinylpyrrolidone (PVP) having a molecular weight ranging fromapproximately 2,000 to approximately 1,000,000), ester or ether of anunsaturated alcohol (e.g., vinyl acetate),polyoxyethylenepolyoxypropylene block copolymer, or mixtures thereof. Inone embodiment, the polymer is PVP having a molecular weight of 2,000 to1,000,000. In a preferred embodiment the polymer is polyvinylpyrrolidoneK-17 (typically having an approximate average molecular weight range of7,900-10,800). Polyvinylpyrrolidone can be characterized by its K-value(e.g., K-17), which is a viscosity index. The polymer used in thesuspension vehicle may include one or more different polymers or mayinclude different grades of a single polymer. The polymer used in thesuspension vehicle may also be dry or have a low moisture content.

Generally speaking, a suspension vehicle according to the presentinvention may vary in composition based on the desired performancecharacteristics. In one embodiment, the suspension vehicle may compriseabout 40% to about 80% (w/w) polymer(s) and about 20% to about 60% (w/w)solvent(s). Preferred embodiments of a suspension vehicle includevehicles formed of polymer(s) and solvent(s) combined at the followingratios: about 25% solvent and about 75% polymer; about 50% solvent andabout 50% polymer; about 75% solvent and about 25% polymer.

The suspension vehicle may exhibit Newtonian behavior. The suspensionvehicle is typically formulated to provide a viscosity that maintains auniform dispersion of the particle formulation for a predeterminedperiod of time. This helps facilitate making a suspension formulationtailored to provide controlled delivery of the insulinotropic peptide ata desired rate. The viscosity of the suspension vehicle may varydepending on the desired application, the size and type of the particleformulation, and the loading of the particle formulation in thesuspension vehicle. The viscosity of the suspension vehicle may bevaried by altering the type or relative amount of the solvent or polymerused.

The suspension vehicle may have a viscosity ranging from about 100 poiseto about 1,000,000 poise, preferably from about 1,000 poise to about100,000 poise. The viscosity may be measured at 37° C., at a shear rateof 10⁴/sec, using a parallel plate rheometer. In some embodiments, theviscosity of the suspension vehicle ranges from approximately 5,000poise to approximately 50,000 poise. In preferred embodiments, theviscosity range is between about 12,000 to about 18,000 poise at 33° C.

The suspension vehicle may exhibit phase separation when contacted withthe aqueous environment; however, typically the suspension vehicleexhibits substantially no phase separation as a function of temperature.For example, at a temperature ranging from approximately 0° C. toapproximately 70° C. and upon temperature cycling, such as cycling from4° C. to 37° C. to 4° C., the suspension vehicle typically exhibits nophase separation.

The suspension vehicle may be prepared by combining the polymer and thesolvent under dry conditions, such as in a dry box. The polymer andsolvent may be combined at an elevated temperature, such as fromapproximately 40° C. to approximately 70° C., and allowed to liquefy andform the single phase. The ingredients may be blended under vacuum toremove air bubbles produced from the dry ingredients. The ingredientsmay be combined using a conventional mixer, such as a dual helix bladeor similar mixer, set at a speed of approximately 40 rpm. However,higher speeds may also be used to mix the ingredients. Once a liquidsolution of the ingredients is achieved, the suspension vehicle may becooled to room temperature. Differential scanning calorimetry (DSC) maybe used to verify that the suspension vehicle is a single phase.Further, the components of the vehicle (e.g., the solvent and/or thepolymer) may be treated to substantially reduce or substantially removeperoxides (e.g., by treatment with methionine; see, e.g., U.S., PatentApplication Publication No. 2007-0027105).

The particle formulation, comprising an insulinotropic peptide, is addedto the suspension vehicle to form a suspension formulation. Thesuspension formulation may be prepared by dispersing the particleformulation in the suspension vehicle. The suspension vehicle may beheated and the particle formulation added to the suspension vehicleunder dry conditions. The ingredients may be mixed under vacuum at anelevated temperature, such as from about 40° C. to about 70° C. Theingredients may be mixed at a sufficient speed, such as from about 40rpm to about 120 rpm, and for a sufficient amount of time, such as about15 minutes, to achieve a uniform dispersion of the particle formulationin the suspension vehicle. The mixer may be a dual helix blade or othersuitable mixer. The resulting mixture may be removed from the mixer,sealed in a dry container to prevent water from contaminating thesuspension formulation, and allowed to cool to room temperature beforefurther use, for example, loading into an implantable, drug deliverydevice, unit dose container, or multiple-dose container.

The suspension formulation typically has an overall moisture content ofless than about 10 wt %, preferably less than about 5 wt %, and morepreferably less than about 4 wt %.

The suspension formulations of the present invention are exemplifiedherein below with reference to exenatide and GLP-1(7-36)amide asexemplary insulinotropic peptides (see, Example 3 and Example 4). Theseexamples are not intended to be limiting.

In summary, the components of the suspension vehicle providebiocompatibility. Components of the suspension vehicle offer suitablechemico-physical properties to form stable suspensions of, for example,dry powder particle formulations. These properties include, but are notlimited to, the following: viscosity of the suspension; purity of thevehicle; residual moisture of the vehicle; density of the vehicle;compatibility with the dry powders; compatibility with implantabledevices; molecular weight of the polymer; stability of the vehicle; andhydrophobicity and hydrophilicity of the vehicle. These properties canbe manipulated and controlled, for example, by variation of the vehiclecomposition and manipulation of the ratio of components used in thesuspension vehicle.

3.0.0 DELIVERY OF SUSPENSION FORMULATIONS

The suspension formulations described herein may be used in animplantable, drug delivery device to provide sustained delivery of acompound over an extended period of time, such as over weeks, months, orup to about one year. Such an implantable drug delivery device istypically capable of delivering the compound at a desired flow rate overa desired period of time. The suspension formulation may be loaded intothe implantable, drug delivery device by conventional techniques.

The suspension formulation may be delivered, for example, using anosmotically, mechanically, electromechanically, or chemically drivendrug delivery device. The insulinotropic peptide is delivered at a flowrate that is therapeutically effective to the subject in need oftreatment by the insulinotropic peptide.

The insulinotropic peptide may be delivered over a period ranging frommore than about one week to about one year or more, preferably for aboutone month to about a year or more, more preferably for about threemonths to about a year or more. The implantable, drug delivery devicemay include a reservoir having at least one orifice through which theinsulinotropic peptide is delivered. The suspension formulation may bestored within the reservoir. In one embodiment, the implantable, drugdelivery device is an osmotic delivery device, wherein delivery of thedrug is osmotically driven. Some osmotic delivery devices and theircomponent parts have been described, for example, the DUROS® deliverydevice or similar devices (see, e.g., U.S. Pat. Nos. 5,609,885;5,728,396; 5,985,305; 5,997,527; 6,113,938; 6,132,420; 6,156,331;6,217,906; 6,261,584; 6,270,787; 6,287,295; 6,375,978; 6,395,292;6,508,808; 6,544,252; 6,635,268; 6,682,522; 6,923,800; 6,939,556;6,976,981; 6,997,922; 7,014,636; 7,207,982; 7,112,335; 7,163,688; U.S.Patent Publication Nos. 2005-0175701, 2007-0281024, and 2008-0091176).

The DUROS® delivery device typically consists of a cylindrical reservoirwhich contains the osmotic engine, piston, and drug formulation. Thereservoir is capped at one end by a controlled-rate water-permeablemembrane and capped at the other end by a diffusion moderator throughwhich drug formulation is released from the drug reservoir. The pistonseparates the drug formulation from the osmotic engine and utilizes aseal to prevent the water in the osmotic engine compartment fromentering the drug reservoir. The diffusion moderator is designed, inconjunction with the drug formulation, to prevent body fluid fromentering the drug reservoir through the orifice.

The DUROS® device releases a therapeutic agent at a predetermined ratebased on the principle of osmosis. Extracellular fluid enters the DUROS®device through a semi-permeable membrane directly into a salt enginethat expands to drive the piston at a slow and even delivery rate.Movement of the piston forces the drug formulation to be releasedthrough the orifice or exit port at a predetermined sheer rate. In oneembodiment of the present invention, the reservoir of the DUROS® deviceis load with a suspension formulation of the present invention,comprising, for example, GLP-1(7-36)amide or exenatide, wherein thedevice is capable of delivering the suspension formulation to a subjectover an extended period of time (e.g., about 3, about 6, or about 12months) at a pre-determined, therapeutically effective delivery rate.

Implantable devices, for example, the DUROS® device, provide thefollowing advantages for administration of a beneficial agentformulation: true zero-order release of the beneficial agentpharmacokinetically; long-term release period time (e.g., up to about 12months); and reliable delivery and dosing of a beneficial agent.

Other implantable, drug delivery devices may be used in the practice ofthe present invention and may include regulator-type implantable pumpsthat provide constant flow, adjustable flow, or programmable flow of thecompound, such as those available from Codman & Shurtleff, Inc.(Raynham, Mass.), Medtronic, Inc. (Minneapolis, Minn.), and TricumedMedinzintechnik GmbH (Germany).

Implantable devices, for example, the DUROS® device, provide thefollowing advantages for administration of the suspension formulationsof the present invention: true zero-order release of the insulinotropicpeptide pharmacokinetically; long-term release period time (e.g., up toabout 12 months); and reliable delivery and dosing of the insulinotropicpeptide.

The amount of beneficial agent employed in the delivery device of theinvention is that amount necessary to deliver a therapeuticallyeffective amount of the agent to achieve the desired therapeutic result.In practice, this will vary depending upon such variables, for example,as the particular agent, the site of delivery, the severity of thecondition, and the desired therapeutic effect. Typically, for an osmoticdelivery device, the volume of a beneficial agent chamber comprising thebeneficial agent formulation is between about 100 μl to about 1000 μl,more preferably between about 120 μl and about 500 μl, more preferablybetween about 150 μl and about 200 μl.

Typically, the osmotic delivery device is implanted within the subject,for example, subcutaneously. The device(s) can be inserted in either orboth arms (e.g., in the inside, outside, or back of the upper arm) orinto the abdomen. Preferred locations in the abdomen are under theabdominal skin in the area extending below the ribs and above the beltline. To provide a number of locations for insertion of one or moreosmotic delivery device within the abdomen, the abdominal wall can bedivided into 4 quadrants as follows: the upper right quadrant extending5-8 centimeters below the right ribs and about 5-8 centimeters to theright of the midline, the lower right quadrant extending 5-8 centimetersabove the belt line and 5-8 centimeters to the right of the midline, theupper left quadrant extending 5-8 centimeters below the left ribs andabout 5-8 centimeters to the left of the midline, and the lower leftquadrant extending 5-8 centimeters above the belt line and 5-8centimeters to the left of the midline. This provides multiple availablelocations for implantation of one or more devices on one or moreoccasions.

The suspension formulation may also be delivered from a drug deliverydevice that is not implantable or implanted, for example, an externalpump such as a peristaltic pump used for subcutaneous delivery in ahospital setting.

The suspension formulations of the present invention may also be used ininfusion pumps, for example, the ALZET® (DURECT Corporation, Cupertino,Calif.) osmotic pumps which are miniature, infusion pumps for thecontinuous dosing of laboratory animals (e.g., mice and rats).

The suspension formulations of the present invention may also be used inthe form of injections to provide highly concentrated bolus doses ofbiologically active insulinotropic peptides.

In one embodiment of the present invention, the continuous delivery of,for example, derivatives and analogues of GLP-1 that have shorthalf-lives after injection into humans (e.g., GLP-1(7-36)amide orexenatide) from an implantable device would be particularly beneficial.Further, the use of an implantable device, such as the DUROS® device, todeliver insulinotropic peptides could reduce injection-relatedside-effects and, with increased convenience of dosing, result inincreased treatment compliance. The duration of drug delivery from oneimplant may be weeks or as long as one year.

Some advantages and benefits of the suspension formulations of thepresent invention delivered via an osmotic delivery device, such as aDUROS® device, include, but are not limited to the following. Increasedtreatment compliance can result in better efficacy and such increasedcompliance can be achieved using an implanted osmotic delivery device.Efficacy of treatment can be improved because an implantable osmoticdevice, such as a DUROS® device, can provide continuous and consistentdelivery of drug (e.g., GLP-1 or exenatide) 24 hours per day to providebetter control of blood glucose levels day and night. Further, it isbelieved that incretins and incretin mimetics may protect the beta cellsin the pancreas and slow down the progression of type 2 diabetesmellitus. Twenty-four hour continuous and consistent drug delivery ofincretins or incretin mimetics from the DUROS® device thus can provideeven greater protection of the beta cells and may provide reversal ofthe disease progression. Continuous delivery of insulinotropic peptides(e.g., GLP-1 or exenatide) from the DUROS® device also allows treatedsubjects complete flexibility in planning meals and thus an increasedquality of life compared to, for example, treatment with bolusinjections that need to be timed relative to the major meals of the day.Also, unlike other sustained release formulations and depot injections,drug dosing when using a DUROS® device can be immediately halted byremoval of the device, for example, if a safety issue arises for aparticular subject.

In addition to GLP-1 derivatives and analogues demonstratinginsulinotropic action, other derivatives of GLP-1 (e.g., GLP-1(9-36)amide) have been shown to reduce blood glucose by a mechanism that doesnot involve insulin secretion (Deacon, C. F., et al., Am. J. Physiol.Endocrinol. Metab. 282:E873-E879 (2002)). Further, GLP-1(9-36) amide hasbeen shown to reduce postprandial glycemia independently of gastricemptying and insulin secretion (Meier, J. J., et al., Am. J. Physiol.Endocrinol. Metab. 290:E1118-E1123 (2006)). Accordingly, in anotheraspect, the present invention includes formulation of such GLP-1derivatives into particles, suspension of the particles in a vehicle,and delivery of these suspension formulations to subjects to reduceblood glucose and/or to reduce postprandial glycemia essentially asdescribed herein above for GLP-1 derivatives and analogues demonstratinginsulinotropic action. In addition, GIP(3-42) appears to be a weak GIPreceptor antagonist that does not exert insulin-related glucoregulation.Such GIP derivatives may also be formulated (singly or in combinationwith other peptides) following the guidance presented herein.

The present invention also includes methods of manufacturing theformulations of the present invention, including the particleformulations, suspension vehicles, and suspension formulations describedherein above.

4.0.0 SUSPENSION FORMULATION USES

The suspension formulations as described herein provide promisingalternatives to insulin therapy for subjects with diabetes mellitus.Diabetes mellitus type 2 or Type 2 Diabetes (also callednon-insulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes)is a metabolic disorder that is primarily characterized by insulinresistance, relative insulin deficiency and hyperglycemia. Thesuspension formulations of the present invention, comprisinginsulinotropic peptides, are useful for stimulating insulin secretion,suppressing glucagon secretion, slowing gastric emptying, and possiblyenhancing insulin sensitivity in peripheral tissues such as muscle andfat.

The suspension formulations of the present invention may be useful inthe treatment of diabetes (e.g., diabetes mellitus, and gestationaldiabetes), and diabetic related disorders (e.g., diabeticcardiomyopathy, insulin resistance, diabetic neuropathy, diabeticnephropathy, diabetic retinopathy, cataracts, hyperglycemia,hypercholesterolemia, hypertension, hyperinsulinemia, hyperlipidemia,atherosclerosis, and tissue ischemia, particularly myocardial ischemia),as well as, hyperglycemia (e.g., related to treatment with medicationsthat increase the risk of hyperglycemia, including beta blockers,thiazide diuretics, corticosteroids, niacin, pentamidine, proteaseinhibitors, L-asparaginase, and some antipsychotic agents), reducingfood intake (e.g., treating obesity, controlling appetite, or reducingweight), stroke, lowering plasma lipids, acute coronary syndrome,hibernating myocardium, regulating gastrointestinal motility, andincreasing urine flow.

In addition, the suspension formulations of the present invention may bepotential regulators of appetite in subjects treated with theformulations.

In one embodiment, suspension formulations are administered using anosmotic delivery device as described above. Examples of target rates ofdelivery for suspension formulations of the present invention,comprising insulinotropic peptides, include, but are not limited to:suspension formulations comprising particle formulations comprisingGLP-1 (e.g., GLP-1(7-36)amide), between about 20 μg/day and about 900μg/day, preferably between about 100 μg/day and about 600 μg/day, forexample, at about 480 μg/day; and suspension formulations comprisingparticle formulations comprising exenatide, between about 5 μg/day andabout 320 μg/day, preferably between about 5 μg/day and about 160μg/day, for example, at about 10 μg/day to about 20 μg/day. An exitsheer rate of the suspension formulation from the osmotic deliverydevice is determined such that the target daily target delivery rate ofthe insulinotropic peptide is reasonably achieved by substantiallycontinuous, uniform delivery of the suspension formulation from theosmotic delivery device. Examples of exit sheer rates include, but arenot limited to, about 1 to about 1×10⁻⁷ reciprocal second, preferablyabout 4×10⁻² to about 6×10⁻⁴ reciprocal second, more preferably 5×10⁻³to 1×10⁻³ reciprocal second.

A subject being treated with the suspension formulations of the presentinvention may also benefit from co-treatment with other agents (e.g.,sulfonylureas, meglitinides (e.g., repaglinide, and nateglinide),metformin, and combinations of such agents), alpha glucosidaseinhibitors, amylin (as well as synthetic analogues such as pramlintide),dipeptidyl peptidase IV (DPP-IV) inhibitors (e.g., sitagliptin andvildagliptin), and long/short acting insulins.

Use of oral dipeptidyl peptidase-IV (DPP-IV or DPP-4) inhibitors orallyto prevent cleavage of GLP-1 may be particularly useful when thesuspension formulation of the present invention comprises a GLP-1variant that is cleavable by dipeptidyl peptidase-IV (see, e.g., U.S.Pat. No. 7,205,409).

Example 5 presents data demonstrating that delivery of a formulationcomprising exenatide using the DUROS® device resulted in decreasedglucose levels and weight loss in treated animals.

Other objects may be apparent to one of ordinary skill upon reviewingthe following specification and claims.

5.0.0 EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use the devices, methods, and formulae of the presentinvention, and are not intended to limit the scope of what the inventorregards as the invention. Efforts have been made to ensure accuracy withrespect to numbers used (e.g., amounts, temperature, etc.) but someexperimental errors and deviations should be accounted for. Unlessindicated otherwise, parts are parts by weight, molecular weight isweight average molecular weight, temperature is in degrees Centigrade,and pressure is at or near atmospheric.

The compositions produced according to the present invention meet thespecifications for content and purity required of pharmaceuticalproducts.

Example 1 Exenatide Particle Formulations

This example describes making exenatide particle formulations.

A. Formulation 1

Exenatide (0.25 g) was dissolved in 50 mM sodium citrate buffer at pH6.04. The solution was dialyzed with a formulation solution containingsodium citrate buffer, sucrose, and methionine. The formulated solutionwas then spray dried using Buchi 290 with 0 7 mm nozzle, outlettemperature of 75° C., atomization pressure of 100 Psi, solid content of2%, and flow rate of 2.8 mL/min. The dry powder contained 21.5% ofexenatide with 4.7% residual moisture and 0.228 g/ml density.

B. Formulations 2 and 3

Two additional formulations of exenatide were prepared essentially bythe method just described. Following here in Table 3 is a summary of theweight percentages (wt %) of the components of the Formulations 1, 2 and3.

TABLE 3 Particle Particle Particle Formulation 1 Formulation 2Formulation 3 Component (wt %) (wt %) (wt %) Exenatide 21.5 11.2 50.0Sodium Citrate* 63.6 74.7 28.4 Citric Acid* 7.1 9.1 3.6 Sucrose 3.9 2.59.0 Methionine 3.9 2.5 9.0 *Sodium Citrate/Citric Acid formed thecitrate buffer for this particle formulation.

Example 2 GLP-1 Dry Powder

This example describes making an GLP-1(7-36)amide particle formulation.GLP-1(7-36)amide (1.5 g) was dissolved in 5 mM sodium citrate buffer atpH 4. The solution was dialyzed with a formulation solution containingsodium citrate buffer and methionine. The formulated solution was thenspray dried using Buchi 290 with 0 7 mm nozzle, outlet temperature of70° C., atomization pressure of 100 Psi, solid content of 1.5%, and flowrate of 5 mL/min. The dry powder contained 90% of GLP-1(7-36)amide.

Example 3 Exenatide Suspension Formulation

This example describes making suspension formulations comprising asuspension vehicle and an exenatide particle formulation.

A. Suspension Formulation of 20 wt % Exenatide Particles

An exenatide particle formulation was generated by spray-drying, andcontained 20 wt % exenatide, 32 wt % sucrose, 16 wt % methionine and 32wt % citrate buffer.

A suspension vehicle was formed by dissolving the polymerpolyvinylpyrrolidone in the solvent benzyl benzoate at approximately a50/50 ratio by weight. The vehicle viscosity was approximately 12,000 to18,000 poise when measured at 33° C. Particles containing the peptideexenatide were dispersed throughout the vehicle at a concentration of10% particles by weight.

B. Suspension Formulations of Particle Formulations 1, 2, and 3

A suspension vehicle was formed by dissolving the polymerpolyvinylpyrrolidone K-17 (typically having an approximate averagemolecular weight range of 7,900-10,800) in the solvent benzyl benzoateheated to approximately 65° C. under a dry atmosphere and reducedpressure at approximately a 50/50 ratio by weight. The vehicle viscositywas approximately 12,000 to 18,000 poise when measured at 33° C.Particle formulations 1-3, described in Example 1, were dispersedthroughout the vehicle at the concentrations (by weight percent) shownin Table 4.

TABLE 4 Suspension Suspension Suspension Formulation 1 Formulation 2Formulation 3 Component (wt %) (wt %) (wt %) Particle Formulation 121.40 — — Particle Formulation 2 — 11.73 — Particle Formulation 3 — —10.05 Polyvinylpyrrolidone 39.30 44.13 44.98 Benzyl Benzoate 39.30 44.1344.98

Example 4 GLP-1 (7-36)amide Formulation

This example describes making a suspension formulation comprising asuspension vehicle and an GLP-1(7-36)amide particle formulation. AGLP-1(7-36)amide particle formulation was generated by spray-drying, andcontained 90 wt % GLP-1, 5 wt % methionine and 5 wt % citrate buffer.

A suspension vehicle containing the polymer polyvinylpyrrolidone wasdissolved in the solvent benzyl benzoate at approximately a 50/50 ratioby weight. The vehicle viscosity was approximately 12,000 to 18,000poise when measured at 33° C. Particles containing the peptideGLP-1(7-36)amide were dispersed throughout the vehicle at aconcentration of 33% particles by weight.

Example 5 Continuous Delivery of Exenatide Using the DUROS® DeviceResulted in Decreased Glucose Levels and Weight Loss in Treated Animals

The data in this Example demonstrated the effect of continuous andconsistent delivery of an exenatide formulation from the DUROS® deviceon glucose levels and weight in the Zucker Diabetic Fatty (ZDF) ratmodel of type 2 diabetes.

The ZDF rat model has been previously described as an accurate model forType 2 diabetes based on impaired glucose tolerance caused by theinherited obesity gene mutation which leads to insulin resistance (see,e.g., Clark, J., et al., Proc. Soc. Exp. Biol. Med. 173: 68-75 (1983);Peterson, R. G., et al., ILAR News 32: 16-19 (1990); Peterson, R. G., InFrontiers in Diabetes Research. Lessons from Animal Diabetes III, editedby E. Shafrir, pp. 456-458. London: Smith-Gordon (1990); Vrabec, J. T.,Otolaryngol Head Neck Surg 118: 304-308 (1998); Sparks, J. D., et al.,Metabolism 47: 1315-1324 (1998)).

The study design presented in Table 5 was used.

TABLE 5 Treatment ZDF Rate Number of Group (mcg*/day) Type Males 1Control Obese 6 2 20 Obese 6 3 20 Lean 6 *micrograms

Rats (Group 2, obese, and Group 3, lean, n=6/group) in treatment groupswere exposed to 20 mcg/day of exenatide (Suspension Formulation 2;Example 3, Table 4) continuously delivered using DUROS® devices forseven 24 hour periods (wherein the device was inserted on day 1 andremoved on day 8), while placebo devices were inserted into rats in thecontrol group (Group 1; n=6). The DUROS® devices were insertedsubcutaneously into each of the animals.

Over the treatment period the following endpoints were evaluated.Clinical signs/Mortality were assessed at least once daily. Body weightwas determined prior to implantation, daily during the observationperiod, and at termination. Blood glucose was determined as follows:fasted blood samples collected on Days −1 and 8; and un-fasted bloodsamples were taken three times each day (4-6 hours apart) Days −1 and 8,with two un-fasted blood samples taken on Days −1 and 8. Blood glucosewas determined using a OneTouch Ultra® (Johnson & Johnson, NewBrunswick, N.J.) blood glucose meter. Glucose levels were measured threetimes per day. Quantitative HbAlc was determined for fasted bloodsamples collected on Days −1 and 8 using a DCA 2000 Plus Analyzer (GMI,Inc., Ramsey, Minn.). Serial blood samples were obtained pre-Implant(0), at 12, 24, 36, 48, 72 hours and at Days 5 and 7 after implantation.These samples were centrifuged, the plasma harvested, and stored at −70°C. Necropsy included macroscopic examination performed on Day 8 of theobservation period.

FIG. 2 presents the data obtained for group mean body weights (ingrams). Decreased body weight was observed in both obese (FIG. 2; closedsquares) and lean (FIG. 2; closed triangles) rats treated with exenatideby Day 4 (Obese: Day 1=329±15.2 g versus Day 4=296.2±14.2 g (p<0.01);and lean: Day 1=265.4±9.1 g versus Day 4=237.6±7.8 g (p<0.01)). Overall,there was a 10.7% weight loss in obese treated rats and a 15.1% weightloss in lean treated rats by Day 6. In contrast, obese rats with placebodevices (FIG. 2; closed diamonds) showed a slight increase (1.8%) inbody weight by Day 6.

FIG. 3 presents the data obtained for group mean blood glucoseconcentrations (in mg/dL). Decreased blood glucose levels were apparentin obese treated rats (FIG. 3; closed squares) compared to obesecontrols (FIG. 3; closed diamonds) within 1 day after DUROS® deviceinsertion. Starting at Day 3 mean glucose levels in obese treated ratswere 163±92 mg/dL, while obese control rats were 481±47 mg/dL (p<0.05).Between Days 3-7, obese rats treated with 20 mcg/day of exenatide haddecreased blood glucose levels that approached those in lean animals,while placebo-treated obese rats had mean glucose levels of 502 mg/dL.Lean animals (FIG. 3; closed triangles) were consistently around glucoselevels of 100 mg/dL. A glucose level of 100 mg/dL is considered to benormal.

FIG. 4 presents the data obtained for group mean blood HbAlc values.Treated obese rats (FIG. 4; closed squares) showed an overall increaseof 5.8% in HbAlc levels, while obese control rats (FIG. 4; closeddiamonds) showed an increase of 6.7% over the study period. Even thoughthere was a decrease of mean blood glucose concentrations over time forthe treated obese rats there did not appear to be a correspondingdecrease in HbAlc in these animals. This result is likely because thestudy was not long enough as HbAlc levels are proportional to averageblood glucose concentrations over one to two month periods.

These data demonstrated that continuous, uniform delivery of exenatideresulted in glucose-lowering together with a potent effect on bodyweight in treated animals. These results support the use of the DUROS®device for long-term steady state dosing of incretin mimetics, forexample, a suspension formulation comprising exenatide, in the treatmentof human diabetes.

As is apparent to one of skill in the art, various modification andvariations of the above embodiments can be made without departing fromthe spirit and scope of this invention. Such modifications andvariations are within the scope of this invention.

1. A suspension formulation suitable for use in a delivery device, thesuspension formulation comprising: a particle formulation comprising: aninsulinotropic peptide; a carbohydrate; an antioxidant; and a buffer;and a non-aqueous, single-phase suspension vehicle that consistsessentially of about 20 wt % to about 60 wt % solvent and about 80 wt %to about 40 wt % pyrrolidone, wherein: the solvent is at least one oflauryl lactate, lauryl alcohol, and benzyl benzoate the suspensionvehicle exhibits viscous fluid characteristics; and the particleformulation is dispersed in the vehicle.
 2. (canceled)
 3. (canceled) 4.The suspension formulation of claim 1, wherein the insulinotropicpeptide is at least one of exenatide, a derivative of exenatide, and ananalogue of exenatide.
 5. (canceled)
 6. The suspension formulation ofclaim 1, wherein the buffer is selected from at least one of citrate,histidine, succinate, and tris.
 7. (canceled)
 8. The suspensionformulation of claim 1, wherein the carbohydrate is at least one oflactose, sucrose, trehalose, cellobiose, and raffinose.
 9. (canceled)10. The suspension formulation of claim 1, wherein the solvent is benzylbenzoate.
 11. (canceled)
 12. The suspension formulation of claim 1,wherein the pyrrolidone is polyvinylpyrrolidone.
 13. (canceled) 14.(canceled)
 15. (canceled)
 16. A delivery device comprising thesuspension formulation of claim
 1. 17. A method of treating type IIdiabetes in a subject in need of such treatment, the method comprising:delivering the suspension formulation of claim 1 from a delivery deviceat a substantially uniform rate for a period of about one month to aboutone year.
 18. The method of claim 17, wherein the period is about threemonths to about one year.
 19. The method of claim 17, wherein thedelivering the suspension formulation is at a dose of 20 μg/day of theinsulinotropic peptide.
 20. A method of manufacturing a delivery device,the method comprising: loading the suspension formulation of claim 1into a reservoir of the delivery device. 21-35. (canceled)
 36. Thesuspension formulation of claim 1, wherein the suspension vehicle has aviscosity of about 5,000 poise to about 50,000 poise at 37° C.
 37. Thesuspension formulation of claim 1, wherein the antioxidant ismethionine.
 38. The suspension formulation of claim 1, wherein eachparticle of the particle formulation has a diameter of about 3 μm toabout 50 μm.
 39. The suspension formulation of claim 1, wherein theparticle formulation is chemically and physically stable for at leastone month to at least one year at a delivery temperature of about 37° C.to about 40° C.
 40. The suspension formulation of claim 1, wherein theparticle formulation is chemically and physically stable for at leastthree months to at least two years at a storage temperature of about 5°C. to about 25° C.
 41. A method of manufacturing the suspensionformulation of claim 1, the method comprising: forming particles of theparticle formulation using at least one of spray drying andlyophilization, such that the particles are substantially uniform inshape and size.
 42. The delivery device of claim 16, wherein thedelivery device delivers the suspension formulation at least one ofosmotically, mechanically, electromechanically, and chemically.
 43. Thedelivery device of claim 16, wherein the delivery device has a deliveryorifice with a first diameter of about 100 μm to about 500 μm, and eachparticle of the particle formulation has a second diameter of about 3 μmto about 50 μm.
 44. The delivery device of claim 16, wherein thedelivery device has a reservoir for receiving the suspensionformulation, the reservoir having a volume less than or equal to 100 μl.